Table 2. Stop signal performance.

Group	Control	Opioid Dependent
	HC	MMT	OD-
	(n = 64)	(n = 65)	combined
			(n = 264)
				OD-long	OD-short
				(n = 156)	(n = 108)
Go response rate (%)	96.8±1.8	96.7±1.8	96.5±1.6	96.4±1.6	96.6±1.7
median Go RT (ms)	615±138	609±121	704±101	721±83	676±119
Stop error rate (%)	52.1±2.5	52.2±2.4	52.6±1.9	52.7±1.9	52.5±2.0
SSRT (ms)	215±59†	217±57# ‡	325±79† #	343±63‡	298±94‡
PES (ms)	55±50†	26±78	28±61†	28±57	27±68

Abbreviations: RT: reaction time; SSRT: stop signal reaction time; PES: post-error slowing.

^† P<.05 between HC and OD-combined groups (post-hoc Tukey tests).

^# P<.05 between MMT and OD-combined groups (post-hoc Tukey tests).

^‡ P<.05 between MMT vs. OD-long, MMT vs. OD-short, and OD-long vs. OD-short subgroups (post-hoc Tukey tests).